1. Field of the Invention
This invention relates generally to electromechanical power converters, and more particularly to an internal impedance converting superconducting acyclic power converters.
2. Description of the Related Art
For a general understanding of the present invention, the following brief background of electromechanical power converters, acyclic machinery, and a historical perspective of electromagnetic machinery is presented.
The creation of magnetomotive force (MMF) in electrical conductor assemblies in the presence of a magnetic field by the flow of current in the electrical conductor assemblies causes translation of the electrical conductor assemblies with respect to the magnetic field. An apparatus used to produce a motive force using electrical current flow is commonly known as an electric motor.
The creation of an electromotive force through the translation of electrical conductor assemblies within a magnetic field is normally termed the generation of electricity from motive force. An apparatus used to generate electricity through the translation of electrical conductor assemblies within a magnetic field is commonly known as an electric generator.
The methods of utilizing electrodynamic interactions, as embodied by a motor in the case of magnetomotive force, or as embodied by a generator in the case of electromotive force, and their resultant apparatus embodiments may be divided into two classes, depending upon the temporal characteristics of the particular electrodynamic interactions utilized.
The first class of electrodynamic interactions, upon which the preponderance of present day electromagnetic machinery is based, can be termed cyclic. This terminology relates to the time varying (cyclical) nature of the electrodynamic interactions employed (at the macroscopic level). That is, there are cyclical electrodynamic interactions that effect either the production of Magnetomotive force or Electromotive Force within the apparatus (machine). Further, it is not at all relevant whether the cyclic apparatus utilizes or produces direct current or alternating current, as all cyclic machines are inherently dependent on time-variant electrodynamic interactions, and as such all cyclic machines are all based on alternating current or a form of time varying current. Today's direct current machines simply rely on commutation/switching means in order to appear as a direct current apparatus to the external world. Commutation or switching may be performed mechanically or electronically. Modern day direct current machine interactions are only quasi time-invariant during the time that a conductor element is translating (sweeping) through the mostly uniform magnetic field present under a salient pole of such a machine.
The second class of electrodynamic interactions are those that can be termed acvelic. This terminology relates to the time invariant (acyclical) nature of the electrodynamic interactions employed (at the macroscopic level). That is, there are acyclical (or continuous) electrodynamic interactions that effect either the production of magnetomotive force or electromotive force within the apparatus (machine.) Inherently, in all acyclic topologies, all macroscopic electrodynamic interactions are deemed to be time-invariant, that is, neither their polarity nor their intensity changes over time.
Acyclic machines have frequently been called homopolar, relating to having magnetic poles on the same center, or are sometimes referred to as Faraday machines, and have also been erroneously called unipolar (having one magnetic pole, which is incorrect, as all electromagnetic apparatus require and do indeed have, at least two opposing magnetic poles.)
Acyclic machines are the only true type of direct current apparatus in existence. Acyclic machines dispense with the many inefficiencies of cyclic alternating current machines, and further eliminate the need for expensive, cumbersome and maintenance prone commutation and switching devices used in today's “direct current” machines.
The present invention relates to the field of acyclic electromagnetic motors and generators that operate without the need for commutation or switching of electrical currents, and to acyclic electromagnetic motors and generators that utilize superconducting material to cause internal impedance change.
Of necessary and relevant background to understanding and describing the present invention is a brief overview of the development of electrodynamics as it relates to electromagnetic machinery in general, and to acyclic machinery in particular, along with a discussion on how acyclic machinery has essentially been ignored in favor of more complex cyclical machinery.
In 1821, Faraday secured the rotary motion of a conductor carrying a DC electric current within a uniform, homogenous and radially symmetric magnetic field. He had discovered the continuous rotary electrodynamic production of magnetomotive force with an apparatus having a homopolar and acyclic topology. Faraday subsequently produced this “electromagnetic rotator” for shipment to other scientists, in order that they may reproduce his experimental results. Faraday went on to cause a magnet to revolve about the axis of a current-carrying conductor in 1821. These were certainly the world's first electric motors, being electromechanical converters for producing mechanical work from the flow of electricity.
Faraday's original homopolar/acyclic “electromagnetic rotator” effect was not investigated or pursued as a potential electric motor, primarily because of the large amount of DC current it required in order to operate due to its very low impedance. This lack of interest persisted in spite of the fact that the Faraday electromagnetic rotator required no complicated switching mechanism such as the solenoids used in the reciprocating “electric motors” of the time. Similar complicated switching mechanisms still exist in many of the direct current machines of today.
The continuous rotary electrodynamic production of electromotive force was first observed in 1831, also by Faraday. Again, Faraday secured the rotation of a conductor (in this case, a conductive disk) within a magnetic field and discovered that an electromotive force was “induced” between the center axis of the rotating disk and its periphery. When an external circuit was completed between the two points, an electric current was seen to flow. In this instance, Faraday had discovered the production of electromotive force with an apparatus having a homopolar and acyclic topology. This was the world's first direct-current electric generator, an electromechanical converter for producing electric current flow from the input of mechanical work.
Faraday's original homopolar generator was also not pursued as a potential electric generator, once again because it produced large amounts of DC current at low voltages due to its characteristic low impedance.
From their inception and discovery, acyclic topologies for producing magnetomotive force or electromotive force have only been lightly investigated in comparison to conventional cyclic rotary electromechanical power converters. Due to their seemingly inherent low impedance, both acyclic generators and motors have to this day been relegated, for the most part, to laboratory use and specialty applications requiring low voltages and high currents.
Between 1900 and the present, there have been some notable developments in the field of acyclic generators and acyclic motors. In 1904, Noeggerath performed experiments attempting to produce higher DC voltages using a homopolar topology, wherein he series-connected multiple electromotive force inducing elements via slip-rings. This resulted in the successful construction of a 500 volt, 300 Kilowatt apparatus the same year. In 1912, Lamme at Westinghouse, designed, constructed and supplied a 260 volt, 2 Megawatt apparatus. This machine was used for a few years before it was mothballed because of the lower cost of AC power. In Germany, many firms were also building what was termed at the time unipolar generators. A 10 volt, 5000 amp @3000 RPM machine was constructed in 1913, and was still in service in 1940, being used to test high-current switches and interrupters (referenced in the German text “Unipolarmaschine fur kleine spannungen und hohe strome” published in “Elektrotechnische Zeitschrift, 61. Jahrg. Heft 16, 18. April 1940.)
By about 1920, current collector brush and slip-ring difficulties such as brush and slip-ring voltage drops and I2R losses had halted acyclic development, and the acyclic machine had been overtaken by commutated direct current machinery and later even more so by alternating current generators (alternators) due to their operating safety, reliability and economy. “As an electric generator for lighting and powergrid supply, the acyclic machine had lost its place forever!” (Translated from the German text “Unipolarmaschine fur kleine spannungen und hohe strome” published in “Elektrotechnische Zeitschrift, 61. Jahrg. Heft 16, 18. April 1940.)
For almost twenty years, acyclic methods and machinery lay dormant again. In reference texts, acyclic and homopolar machinery was given short and shrift treatment, generally with the remark that they failed due to the abovementioned brush/slip-ring and I2R problems. Due to the needs of the chemical industry just before WWII, there was a brief renewed interest in acyclic direct current generation, especially in Germany, where in 1935, a 7.5 volt, 150,000 amp@514 RPM machine was constructed. This machine was similar to machines constructed prior to WWI, in that it employed insulated conductors embedded into armature slots with brushes and slip-rings to provide the series electromotive force summation of multiple electromotive force inducing armature elements (referenced in the German text “Unipolarmaschine fur kleine spannungen und hohe strome” published in “Elektrotechnische Zeitschrift, 61. Jahrg. Heft 16, 18. April 1940.)
Much simpler in construction was an apparatus first proposed by Poirson, who in 1930 built a 7 volt, 15,000 amp@1800 RPM machine and then a second, substantially larger machine rated at 14 volt, 50,000 amp@750 RPM. This machine was demonstrated at the Paris World Exhibition in 1937. Both of these designs utilized a non-slotted rotor, which served as the armature core, slip-ring and electromotive force producing conductor (referenced in the German text “Unipolarmaschine fur kleine spannungen und hohe strome” published in “Elektrotechnische Zeitschrift, 61. Jahrg. Heft 16, 18. April 1940.)
After another dormancy period of 1940 to 1960, acyclic topologies again became a topic of interest, when General Electric and the US Navy investigated acyclic motors and generators for their potential applications in marine propulsion. An example of such a machine was an acyclic generator rated at 67V, 150000 A@3600 RPM, produced by General Electric in 1964, as mentioned in the text “Electromechanical Power Conversion” by Levi and Panzer, 1974.
Also, from the mid-1960's to the present, superconducting and high-temperature superconducting (HTS) field coil designs and liquid-metal (eutectic) current collector brushes, have been introduced, developed and utilized in specific high-power applications such as fusion research, rail-gun launchers, welding, and the like. For example, the Center for Electromechanics (CEM) at the University of Texas at Austin has produced both disk and drum-type acyclic generators with outputs ranging from 5 to 10 Megawatts. They have also designed pulsed homopolar welding generators for pipe welding, which were produced by OIME Inc.
More recently, in 1997, the US Navy announced its HTSC (high-temperature super-conducting) acyclic/homopolar marine propulsion motor test results. Also in 1997, CEM and Parker Kinetic Designs announced their work on an acyclic traction motor for automobiles and locomotives. And even more recently (2002-2005), the US Navy announced further investigation of acyclic marine propulsion motors employing High Temperature Superconducting field coils using General Atomics' 5 Megawatt and 36 Megawatt machines.
Recently, acyclic machines employing rolling contacts that eliminate sliding current collectors have been introduced, and homopolar (but bipolar, and not acyclic) apparatus employing multiple microfibre composite metal brushes and multiple current carrying segment commutation have been proposed.
Systems for the electromechanical conversion of power are well known, for the most part concerning cyclical heteropolar topologies, that effect the series summation of magnetomotive force producing current flow through active conductor segments, or effect the series summation of the electromotive force produced in active conductor segments. In both of these heteropolar cases the chosen form for the active conductor assemblies is typically a coiled (or coil-formed) series conductor winding.
There are essentially three groups of related art involving acyclic machines. In Group 1 are the vast majority that do not use or employ series summation of active conductor segments or elements, but are simple single active conductor element apparatus such as disk, drum, cylindrical, bell-shaped, parallel connected drum, sheet stacks, and the like.
Group 2 includes those acyclic topologies which utilize a plurality of active conductor segments or elements and attempt to effect the series summation of produced magnetomotive force or induced electromotive force by utilizing multiple slip-ring/brush assemblies for such electrical series summation, or by utilizing counter-rotating active elements and attendant slip-ring/brush assemblies.
To the inventor's best present knowledge and belief, the following is a summary listing of such Group 2 related art:
U.S. Pat. No. 293,758 (Lubke, 1884); U.S. Pat. No. 339,772 (Hering, 1886); U.S. Pat. Nos. 342,587, 342,588, 342,589, 351,902, 351,903, 351,904, 351,907 and U.S. Pat. No. 352,234 (all to Eickemeyer, 1886); U.S. Pat. No. 406,968 (Tesla, 1889); U.S. Pat. No. 396,149 (Eickemeyer, 1889); U.S. Pat. No. 400,838 (Entz, 1889); U.S. Pat. No. 515,882 (Maynadier, 1894); U.S. Pat. No. 523,998 (Rennerfelt, 1894); U.S. Pat. No. 561,803 (Mayer, 1896); U.S. Pat. No. 645,943 (Dalen et al., 1900); U.S. Pat. No. 678,157 (Bjamason, 1901); U.S. Pat. No. 742,600 (Cox, 1903); U.S. Pat. No. 789,444 and U.S. Pat. No. 805,315 (both to Noeggerath, 1905); U.S. Pat. No. 826,668 (Ketchum, 1906); U.S. Pat. No. 832,742 (Noeggerath, 1906); U.S. Pat. No. 854,756 (Noeggerath, 1907); U.S. Pat. No. 859,350 (Thomson, 1907); U.S. Pat. No. 3,229,133 (Sears, 1966); U.S. Pat. No. 3,465,187 (Breaux, 1969); U.S. Pat. No. 4,097,758 (Jenkins, 1978); U.S. Pat. No. 4,514,653 (Batni, 1985); U.S. Pat. No. 5,241,232 (Reed, 1993); and U.S. Pat. No. 5,587,618 (Hathaway, 1996.)
An example of recent related art attempting to provide for series summation of induced electromotive force potentials in acyclic generators (or of magnetomotive force in motors) is U.S. Pat. No. 5,241,232 to Reed, which utilizes a conductive belt between two or more active elements in order to provide for such series summation. The apparatus of the Reed patent is similar to that of Tesla from more than 100 years prior, in that they both utilize a flexible conductive belt to electrically connect two co-rotating active elements in series.
Another recent example is U.S. Pat. No. 5,587,616 to Hathaway, which utilizes a complex plurality of synchronously counter-rotating armatures and associated slip-rings and sliding contacts in order to provide for series summation.
The group 2 related art as described above attempts to create series summation using various complex and cumbersome techniques requiring multiple elements. The present invention improves upon the group 2 related art by using a single active element within the same total overall intensity magnetic flux field.
Group 3 related art contains those acyclic topologies which utilize a multiplicity of active conductor segments or elements and attempts to effect the series summation of produced magnetomotive force or induced electromotive force by utilizing some form of “series winding” or “series arrangement” of said multiple active conductor segments or elements, thereby attempting to provide such series summation directly.
To the inventor's best present knowledge, the following is a summary listing of such Group 3 related art:
U.S. Pat. No. 5,278,470 (Neag, 1994); U.S. Pat. No. 5,451,825 (Strohm, 1995); and U.S. Pat. No. 5,977,684 (Lin, 1999.)
The Group 3 related art topologies and apparatus fail, however, to achieve the series summation of induced electromotive force (generator action) or produced magnetomotive force (motor action.) In U.S. Pat. No. 5,278,470 (Neag) and U.S. Pat. No. 5,451,825 (Strohm), the inventions fail to take into account the reverse electromotive forces that will be induced (or reverse magnetomotive force torques that will be produced) due to return flux paths/interlinkages interacting with active conductor segments/elements (whether such interaction was intended or not.)
In the particular case of the Neag patent, FIG. 1A of the Neag patent clearly shows flux paths/interlinkages being completed. In the process however, producing perfectly canceling electromotive forces or magnetomotive forces as the case might be, in the peripheral conductor segments forming part of his series winding on the rotor. The fact that the peripheral conductor segments are sunk into slots in the magnetically permeable rotor will not lead to any appreciable shielding of said conductor segments, and hence will fail to have the rotor series winding produce any measurable electromotive force or magnetomotive force, as the case may be.
In the particular case of the Strohm patent, although FIG. 1 of the Strohm patent implies magnetic flux vectors (B) in opposition to each other, thereby appearing to lead to the desired production of electromotive force or magnetomotive force in conductive elements (when they are translating through said B fields), the complete flux paths and interlinkages are not depicted nor discussed. Accordingly, once the complete flux paths/interlinkages are studied and examined, it is found that perfect electromotive force or magnetomotive force cancellation takes place once again, in almost an identical fashion as in Neag above, due to the interaction of the peripheral series conductor with said completed flux paths/interlinkages. Due to this unfortunate outcome, Strohm's later attempts at the series summation of a plurality of said translating conductive elements will most likely also fail.
In U.S. Pat. No. 5,977,684 to Lin, there will be a lack of desired induced electromotive force (or produced magnetomotive force) due to the fact that the uniform/symmetric axial magnetic flux field will not co-rotate at the input shaft angular velocity, but rather, it will appear to be stationary in the machines rotational (non-inertial) reference frame. Hence, there will not be a “moving” (i.e., rotating) magnetic flux field interacting with active conductor segments in one area, and a “non-moving” (i.e., static) magnetic flux field that is not interacting with series connecting conductor segments in another area. There will only exist static magnetic flux fields.
In summary, for the cases of related art pertaining to the class of electromechanical power converters termed as being of acyclic topology (and homopolar), the methods known and disclosed for series summation as in Group 2 are mostly impractical, and those known and disclosed as in Group 3 are not viable, and have thus contributed to maintaining the image of the acyclic homopolar converter as solely a low-impedance device.
In the past the practical use of acyclic (homopolar) motors and generators has been inhibited by the large voltage drop of conventional graphite-based electrical brushes. Recently, at least in principle, microfiber brushes and hybrid (metal/liquid) brushes, have promised to remove this previously critical bottleneck. However, there are still other problems to overcome. The first obstacle against the widespread use of acyclic (homopolar) machines has been the need for a large number of brushes and brush holders (due to the still very high currents to be handled because of low rotor impedance.) The second obstacle is a very low machine voltage (or rotor impedance), due to the low voltage (electromotive force) per current “turn” or path. For example, passage of current through an active conductive rotor element moving in a magnetic field, for known acyclic (homopolar) machines, rarely exceeds 20 volts per turn. This condition necessitates the use of several to many “turns” or paths, and hence a multiplicity of brushes, brush holders and slip-rings, in order to attain a practical voltage of at least several hundred volts for the overall machine.
To further provide background teaching, the points raised in one of the most comprehensive treatments of homopolar power converter structures (and heteropolar structures as well) published, given by Levi and Panzer in, “Electromechanical Power Conversion” [1974], pp. 152-200 (ch. 5, “Homopolar Converters”) and pp. 201-254 (ch. 6, “Power Conversion in Heteropolar Structures: Synchronous Converters with Uniform Air Gap”.), should be considered.
From the outset, in “Electromechanical Power Conversion” [1974], at p. 8 in the “Introduction”, Levi states “ . . . in Chap. 5 . . . . We find the homopolar converter to be inherently a low-voltage, high-current device . . . . In seeking to overcome the low-impedance limitations of the homopolar converter, we discover in Chap. 6 the advantages arising from a heteropolar configuration”.
In studying Levi above, we find that Chapter 5 deals most thoroughly with the symmetry aspects of cylindrical rotary homopolar structures and some of the unique characteristics associated therewith, for example, because of this symmetry, the induced Magnetic (B) field in a homopolar machine does not generate any motional electric field and that this property is peculiar to homopolar structures, and is not shared by any other structures. Further, the “armature reaction” experienced in a homopolar machine is different than that in all other structures (topologies), so that the homopolar structure is unique and at an advantage compared to other types, in that saturation effects can be easily avoided and almost completely screened out in such homopolar structures.
Chapter 5 also concludes that the homopolar machine is of high-speed, large magnetic (B) field, low-voltage, high-current; and hence inherently low-impedance in nature. Some of the final assumptions given in the summary of Chapter 5, state that, “ . . . we have studied the converter type which has the greatest symmetry and uniformity: the homopolar converter.” and 1.) “The electrical and mechanical performance of the converter as a whole essentially parallels that of a single volume element.” and 2.) “Efficiency considerations limit this application to velocity intervals in the neighborhood of the drift velocity.” and 4.) “When saturation effects are negligible, the armature reaction in endless structures does not affect the terminal voltage . . . ”. The treatment of homopolar machines in Chapter 5 are typical of the treatment given to, and classification of, homopolar structures.
At the beginning of Chapter 6, p. 201, Levi states, “We begin by seeking means to overcome the rigid relation between voltage and physical dimensions in the homopolar converter, and trace the source of this inflexibility in impedance level to the uniformity of the field distribution . . . ”. Subsequently, on pp. 203-207, he states that “the inherent low-impedance of the homopolar converter cannot be overcome in that series summation of the electromotive force in active conductor segments cannot be accomplished.” This argument is also mentioned in further detail elsewhere in the Levi text. Essentially, Levi categorically states that the inherent problem of “bucking” or electromotive force cancellation in series connections cannot be overcome in homopolar machines, hence the subsequent diversion to heteropolar machinery (those producing AC). Levi does touch upon the “Gramme ring winding”, which does effect a specific form of flux “steering” and flux “isolation”, when used in a heteropolar structure in order to effect series summation. Levi indicates that only heteropolar converters are capable of impedance-matching, due to their exclusive ability to use series summation for active conductors.
In the summary of Chapter 6, Levi concludes, 1.) “The low electric impedance of the homopolar converter is inescapable. This drawback has to be overcome by resorting to polarity alternations in the gap B [field], so as to permit increased voltage by series connection of individual armature conductors. An immediate consequence of this heteropolarity is the establishment of AC quantities in the external circuit.”, and also, 2.) “ . . . [in heteropolar converters] . . . the average or net power per-unit surface cannot reach the same ultimate levels as in homopolar converters.” [bracketed italics are the inventors additions].
We refer to Levi's treatment of the subject matter as being representative of the typical arguments and currently dominant opinions proffering the necessity, desirability and superiority of heteropolar structures over homopolar structures. However, we also note his statement of several unarguable peculiarities and advantages exhibited even by the known classical low-impedance homopolar structures.
Throughout Levi above, homopolar really meant acyclic and homopolar; one can have a homopolar structure that is not acyclic, for example, the eddy current brake on a watthour meter. To be acyclic means to be inherently homopolar.
It is thus an object of the present invention to provide for an internal impedance converting electromechanical power converter that uses a conductive shell with superconducting conductors in series to achieve high impedance output.